1. Field of the Invention
The present invention relates to an axial tube assembly of a motor.
2. Description of Related Art
FIG. 1 illustrates a conventional axial tube assembly of a motor, and FIG. 2 is a sectional view of a motor with an axial tube assembly of FIG. 1. As illustrated in FIGS. 1 and 2, the motor includes a casing 1 with an axial tube 11 formed thereon. The axial tube 11 has an axial hole 11, wherein plural slots 112 are defined in a periphery delimiting the axial hole 111 and each include an open end 113. An engaging member 2 includes a ring-like base 21 and plural legs 22 projecting from a side of the base 21. The base 21 is engaged in an annular groove 114 in a bottom end of the axial tube 11, with the respective leg 22 being received in the respective slot 112 and with a hook 23 on a distal end of the respective leg 22 pressing against a side of a stator assembly 3 that is mounted around the axial tube 11. Plural protrusions 115 are formed on the inner periphery of the axial tube 11, with an upper bearing 4 mounted on tops of the protrusions 115, with a lower bearing 4 mounted to bottoms of the protrusions 115, and with a shaft 51 of a rotor 5 extending through the bearings 4.
The legs 22 of the engaging member 2 together hold the bearings 4 in place. Further, the respective leg 22 is pushed outward by the bearings 4, and the hook 23 of the respective leg 22 presses against the side of the stator assembly 3. Thus, the hooks 23 of the legs 22 retain the stator assembly 3 in place. As a result, the bearings 4 are retained in place by the legs 22 of the engaging member 2 such that the rotor 5 rotates about a fixed axis and that the whole stator assembly 3 is reliably fixed regardless of heat expansion/shrinkage of the axial tube 11 due to temperature change. However, the bearings 4 might not be in contact with the inner periphery delimiting the axial hole 111 of the axial tube 11, failing to provide a reliable assembly for the bearings 4. Further, in a case that the bearings 4 are oily bearings, the axial tube 11 and the engaging member 2 could not provide a sealed reservoir for the lubricating oil, resulting in loss of the lubricating oil of the bearings 4. Further, mounting of a retainer 52 to the shaft 51 of the rotor 5 that has been extended through the bearings 4 is difficult, as the space in the axial hole 111 of the axial tube 11 is relatively small. Further, dust is apt to enter the bearings 4 via a relatively large gap between the axial tube 11 and an end wall of the rotor 5.